1. Field of the Invention
The invention also relates to a use of these L-2-oxothiazolidine-4-carboxylic acid derivatives as a precursor of cysteine and of hydroxy acid. The invention also relates to uses of these L-2-oxothiazolidine-4-carboxylic acid derivatives for skincare.
2. Description of the Background
Users of cosmetic and/or dermatological products are increasingly seeking to rejuvenate the skin, i.e. reduce wrinkles and fine lines, brighten the complexion of the face and make the skin supple. These signs of ageing are not only due to age but also especially to exposure to the sun and to other radiation such as artificial tanning by UV rays in particular.
In parallel, these same users are increasingly seeking to lighten the skin.
The active agents known to combat ageing are retinoic acid and derivatives thereof. Unfortunately, these active agents have side effects, such as stinging, heating sensations and causing redness, which are unpleasant for the user and exclude users with sensitive skin from using this type of active agent.
There is thus a need for anti-ageing and/or bleaching agents that are as effective in their action as those in the prior art but that do not exhibit the drawbacks thereof.
Moreover, there are currently very few active agents having depigmenting properties.
L-2-Oxothiazolidine-4-carboxylic acid esters intended to stimulate the intracellular synthesis of glutathione in certain cells of the human body are known from U.S. Pat. No. 5,208,249. These esters comprise a group having from 1 to 10 carbon atoms and is chosen from the methyl, ethyl, propyl, isopropyl, butyl, isobutyl and tert-butyl groups.
Other L-2-oxothiazolidine-4-carboxylic acid esters used as cysteine precursors and in combination with glutathione stimulators to prevent hair loss and to stimulate the growth of new hair are moreover known from EP-A-656,201. These esters have an alkyl group of from 1 to 10 carbon atoms and is chosen from the methyl, ethyl, propyl, butyl, pentyl, hexyl, peptyl, octyl, nonyl, decyl, isopropyl, isobutyl, sec-butyl, tert-butyl and isopentyl groups.